The present invention generally relates to disk apparatus, and more particularly to a disk apparatus in which a disk is rotated by using a constant linear velocity (CLV) method.
Optical disks are used in various fields because of their large memory capacity. Disk driving methods for optical disk apparatuses are classified, in general, into two methods; one is a constant linear velocity (CLV) method and the other is a constant angular velocity (CAV) method.
Whichever one of the above-mentioned methods an optical disk apparatus uses, the optical disk apparatus may be operated in any one of the following states:
1) all functions are inactive except for an interface for an external apparatus (inactive state); PA1 2) a recording/reproducing operation is performed by operating a disk motor, a focusing device and a tracking servo device (active state); and PA1 3) waiting for a command to be supplied for performing a recording/reproducing operation while the disk motor, the focusing device and the tracking servo device are in an active state (standby state). PA1 a disk driving unit for rotating the disk; PA1 a head driving unit for driving the head; PA1 a linear velocity controlling unit for controlling a rotational speed of the disk so that the linear velocity of the head relative to the disk is maintained to be constant; PA1 a constant rotational speed controlling unit for rotating the disk at a constant rotational speed; PA1 a switching unit for switching a control of the disk driving unit to be performed by either one of the linear velocity controlling unit and the constant rotational speed controlling unit; and PA1 a stopping unit for stopping an operation of the head driving unit while the disk driving unit is controlled by the constant rotational speed controlling unit.
The above-mentioned three states are switched by a controller in the optical disk apparatus. The three states are classified basically into two states; one state in which the optical disk apparatus is in an active state (states 2 and 3) and the other state in which the optical apparatus is in an inactive state (state 1). In the states, 2 or 3, in which the optical disk apparatus is active, all functions are activated, and thus a power consumption associated with the functions is large and a large amount of heat is generated. In particular, in the standby state 3, there is a problem in that a power is consumed wastefully and a large amount of heat is generated by the wasteful power consumption because the disk motor, the focusing device and the tracking servo device, which are not in actual use, are activated. Such a wasteful power consumption may be particularly a serious problem for a portable disk apparatus in which a battery is used.
Japanese Laid-Open Patent Applications No. 3-201261 and No. 4-76857 disclose disk apparatuses using a CAV method in which apparatuses the above-mentioned problems are eliminated. These disk apparatuses reduce a power consumption by stopping power supply to a head or stopping operations of a tracking servo circuit and a focusing servo, in turn, after a predetermined time elapses once the disk apparatuses fall into the standby state.
In a disk apparatus using the CAV method, since the disk is always rotated at a constant angular speed, a disk driving system and a head driving system can be controlled separately. Accordingly, in the disk apparatus using a CAV method, a power supply to the head driving system can be stopped in the standby state so that only a disk is rotated, thus reducing a power consumption. This is referred to as a power save mode.
On the other hand, in a disk apparatus using the CLV method, a rotational speed of a disk varies according to a position of a head, and thus a rotational speed of a spindle motor is controlled in accordance with positional information on the disk read out by the head. Due to this, a disk driving system and a head driving system cannot be controlled separately in the disk apparatus using the CLV method.
Accordingly, when a power save mode like that in the disk apparatus using the CAV method is introduced into a disk apparatus using the CLV method, an operation of a disk driving system must be stopped because a head driving system cannot be stopped separately from the disk driving system. Once the disk driving system is stopped, a rotation of the disk must be started up first to return to a regular operation mode from the power save mode. Accordingly, a long time is spent on returning from the power save mode to a regular operation mode, and thus there is a problem in that a response speed is slow making the above-mentioned method not practical for use.